MINOR: haload: support HTTP status code by version

MINOR: haload: support HTTP status code by version

Add support for tracking and displaying HTTP status code distribution
broken down by HTTP version (h0, h1, h2, h3) via the new -hsv option.
Building upon -hs, -hsv retains the global status code distribution and
appends additional columns detailed by HTTP version.

Each URL configuration (struct hld_url_cfg) stores its targeted HTTP version in
->http_ver. Thread statistics track status code counts per HTTP
version in thrs_info.vtot_sc[][], which are then aggregated and displayed
alongside global status codes in hld_summary().

Also remove deprecated --show-status-codes, which is a too long long option,
in favor of -hs / -hsv.